Burner with adjustable air distribution



Aug. 30, 1949. v. z. CARACRISTI BURNER WITH ADJUSTABLE AIR DISTRIBUTION 2 Sheets-Sheet 1 Filed Sept. 19, 1947 INVENTOR.

Virginius Z. Curucristi ZJ"L .4 @w/ Aug. 30, 1949. v. z. CARACRISTI I 80,547

BURNER WITH ADJUSTABLE AIR DISTRIBUTION Filed Sept. 19, 1947 2 Sheets-Sheet 2 Fig.2.

INVENTOR. Virginius Z. Curucrisfl vlW iw Patented Aug. 30, 1949 BURNER WITH ADJUSTABLE AIR DISTRIBUTION Virginius Z. Caracrlsti, Bronxvllle, N. Y., assignmto Combustion Engineerlng-Superheater, Inc., a corporation of Delaware Application September 19, 1947, Serial No. 774,982

2 Claims. 1

This invention relates to burners and particularly to burners of the type in which the air for combustion is admitted through the burner-into the furnace in an annular stream surrounding the fuel stream. The fuel may be such as pulverized coal, a gas, oil or the like.

It has been found that in burners of this type it is important that the distribution of air fiow through the annulus surrounding the fuel stream be substantially uniform, for if this distribution is not uniform, certain portions of the fuel-air mixture issuing into a furnace will get too much air and too little fuel and the burning mixture issuing from the burner will be uneven. Furthermore, when a furnace is associated with a steam boiler, the path of the burning mixture from the mouth of a burner of the above type to the tube bank of the steam boiler is usually relatively short. Consequently the distribution of fuel and air over the cross section of the furnace must be effected at the burner and the distribution of both fuel and air within the burner must be substantially uniform throughout so that the combustion of the entire fuel will be substantially uniform and the furnace volume will be efliciently utilized.

Seen through an observation opening in the furnace wall opposite the burner, the flame from a well designed and properly operated burner of the type here considered appears to radiate from the burner center and from a uniform annular disc.

An object of this invention is to provide improved means for distributing the air uniformly around the fuel stream issuing from a burner of the type under consideration.

Other objects will become apparent from the following description of an illustrative embodiment of the invention when read in conjunction with the accompanying drawings wherein:

Figure 1 is a sectional elevation (as on line l-l of Fig. 2) of a pulverized fuel burner embodying the present invention; and

Figure 2 is an end view of the same apparatus as viewed from the right of Fig. 1 with part of the burner casing broken away.

In the drawings, the main pipe of the burner is designated as a whole by the numeral l and is disposed horizontally, its tip 2 projecting into an aperture 3 in the furnace wall 6. This burner pipe I is cylindrical and provided on its interior with rifling comprising a plurality of helical ribs s extending nearly throughout its length. The burner pipe i has a volute entrance section '5 through which fuel in flotation in primary air is supplied tangentially to the burner nomle through a fuel supply pipe 8.

Secondary air is delivered to the tip of burner pipe i from a windbox 9 through which the burner projects. The nozzle section of burner pipe I is enclosed in a casing ill forming an annular chamber ll surrounding the burner. At its outer end the annular chamber II is in communication with windbox 9 through a circumferential port B2 in the wall of casing Ill. Dampers l3 rotating on shafts it are arranged around the burner in port l2 and each is provided. with an arm l5 having a pin and slot connection to an operating ring 16. As ring it is rotated clock-wise (Fig. 2) the dampers l3 separate with respect to one another and open to permit more secondary air to flow around burner pipe I and when ring 16 is rotated counter-clock-wise the dampers close and reduce the air flow.

In the absence of a sleeve I! over port l2, it has been found that when air enters the windbox 9 in one general direction as downward in 1 a major part of the secondary air supply enters the annular chamber ll around burner pipe I- through the upper part of port l2. Little air enters around other parts of the burner, as at the lower part thereof. This inequality of air supply through port I! around the burner pipe prevails in the travel of the air toward the furnace through the annular chamber II and results in an uneven distribution of the secondary air discharging into the furnace around the burner tip 2. This in turn causes an unbalance in the fuel-air mixture within the furnace and inefficient combustion.

As here provided, sleeve I1 is cylindrically formed to extend inwardly from the outer wall l8 of windbox 9 across the circumferential port I! in burner casing I0. The inner edge of sleeve I1 is substantially in alignment with but spaced from the furnace-side edge of port If to provide an annular opening l9 through which the windbox is in communication with the enclosed space around port l2. Sleeve l'l prevents air from flowing directly into port l2 from the windbox 9 and causes it to flow toward port I! through annular opening 99 around the entire circumference of sleeve IT in a direction substantially parallel to the axis of the burner. Thence the air turns deg. into the port 82 and again 90 deg. into chamber H to pass toward the burner tip 2.

By blocking the direct entry of the air into port I 2 from any direction by means of sleeve ii, the velocity of the air from that direction is diminished and is no longer effective to cause an excess flow of air from that direction into the burner. to enter port I 2 through opening N! at right angles to its direction of flow in windbox 9 and then caused to make abrupt turn into port [2 thereby tending to equalize resistance to air flow into the burner.

Notwithstanding this equalization, I have found that the sleeve l'l alone does not distribute the flow of air through the annular chamber II with sufficient uniformity to assure a satisfactory uniform burning in the furnace. Furthermore, in this type of burner the actual drop in pressure across the ring of dampers i3 is very small, insuilicient to properly influence the distribution around the annular chamber ll.

According to the invention an additional baffle 20 in the form of an annular plate is mounted in a plane substantially normal to the axis of the burner pipe I and is spaced from the annular opening l9 of port [2. Certain of the shafts I4, in this disclosure three designated as Ha, which support dampers l3 are extended beyond the dampers l3 through baffle 20 and serve as supports therefor. Each of these shafts l4a extends freely through the outer wall 18 of wind box 9 and has a threaded portion 2! engaging a nut 22, which is fastened to the casing wall I 8 and is provided with means such as a wheel 23, for turning the shaft Ma.

The other end of each shaft Ma passes inside the baiile 29 and is provided with a reduced portion 24 which freely engages a supporting member 25 fastened to baflle 29 as by bolts 26. The reduced portion 24 of each shaft [4a with its shoulder bearing against one side of member 25 and a nut and washer 2'! bearing against the other side of the member, will oblige the baflle 20 to move with shaft Ma as the shaft is screwed inwardly or outwardly through stationary nut 22. In this manner the spacing of baffle 20 from opening 19 may be varied and therewith the resistance to air flow into port l9.

By adjustment of the three shafts Ma, the

baiiie 29 may be spaced parallel to the plane normal to the burner aXis through port l9, so as to form a uniform circumferential gap for the air to enter port I9, or it may be spaced at an angle to said plane, or may warped with respect thereto. In the latter cases there will result a varying circumferential gap, which may be narrower on the side from which the air flows into it from windbox 9. Obviously the shaft supports 14a for the baflles 20 may be replaced by independent rods I ia.

By my improved baffle 20, any undesirable air distribution into port 19 and subsequently into the annular chamber l I may then be corrected by controllably varying the gap between baflle 29 and the opening of port l9.

Thus, all of the air is then forced While the preferred embodiment of my invention has been shown and described, it will be understood that changes in construction. combination and arrangement of parts may be made without departing from the spirit and scope of the invention as claimed.

I claim:

1. In a burner, a windbox, a. fuel injector pipe projecting horizontally through said wlndbox into a furnace at its inner end, a casing enclosing said pipe to form an annular chamber therearound and having an air inlet port formed in its wall extending substantially completely around said annular chamber adjacent the outer wa l of said windbox, a. sleeve supported within said windbox so as to extend completely across and around said port and spaced from said casing near one end of the port to form an annular air inlet opening to said port, a baflle spaced from and extending across said air inlet opening to said port, and means for adjusting said baflle to vary the space between said bailie and said air inlet opening, said means comprising a multiplicity of rods for supporting said baille from said outer windbox wall and means for independently adjusting the length of each rod extending between said wall and said baille.

2. In a burner comprising a windbox, a fuel imector pipe projecting through said windbox, and a casing enclosing said pipe to form an annular chamber therearound and having an air inlet port formed in its wall extending substan-- tially completely around said annular chamber adjacent the outer wall of said windbox, the combination of a sleeve supported within said windbox so as to extend completely across and around said port and spaced from said casing near one end of the port to form an annular air inlet opening to said port, a bailie spaced from and extending across said air inlet opening to said port, a plurality of members for supporting said baiiie I from said outer windbox wall, and means for independently adjusting the length of each support member between said wall and said bafile whereby controllably'to vary the space between the baffle and said air inlet opening.

VIRGINIUS Z. CARACRIS'I'I.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,698,169 Peabody Jan. 8, 1929 1,799,459 Fantz Apr. '7, 1931 1,966,524 Schenck July 17, 1934 2,379,490 Kruger July 3, 1945 

